1. Field of the Invention
The present invention relates to a motor drive apparatus for an injection molding machine including a servo amplifier connected to a servomotor, and a controller connected to the servo amplifier.
2. Description of the Related Art
Generally, as disclosed in Japanese Patent Application Laid-Open (kokai) No. 2000-37758, a motor-driven injection molding machine includes a motor drive apparatus for driving a servomotor. The motor drive apparatus usually includes a servo amplifier connected to a servomotor, and a controller connected to the servo amplifier. The controller is designed for exclusive use with an injection molding machine and for exchange of various signals with a servomotor to be connected thereto.
Servomotors and servo amplifiers usually have versatility for use with various kinds of machinery and differ in specifications among manufacturers and models. As a result, conventionally, when a servomotor used with an injection molding machine is to be replaced with another servomotor of a different type, the controller must be modified in design accordingly, causing a significant increase in cost and involving additional man-hours for modification.
An object of the present invention is to provide a motor drive apparatus for an injection molding machine requiring no modification of design of a controller even when a servomotor is to be replaced with one of a different type, to thereby achieve a significant reduction in cost and a reduction in man-hours involved in the replacement.
Another object of the present invention is to provide a motor drive apparatus for an injection molding machine having enhanced adaptability and developability and capable of establishing a thin profile.
To achieve the above objects, the present invention provides a motor drive apparatus for an injection molding machine, comprising a servo amplifier connected to a servomotor; a controller connected to the servo amplifier; and an interface unit for selectively connecting the controller to one of a plurality of different servo amplifiers. Even when the servomotor is to be replaced with another, different servomotor, the interface unit can cope with the replacement without need of modification of design of the controller. Specifically, all that is required is selection, from among a plurality of interface printed circuit boards, of an interface printed circuit board corresponding to a servo amplifier for the replacement servomotor.